Foamed metal bodies

ABSTRACT

A foamed metal panel has a tubular core embedded in it to conduct heating liquid or the like. The panel can also be reinforced with metal inserts such as blocks and plates at points of stress.

United States Patent Valdo Nov. 19, 1974 FOAMED METAL BODIES 3,607,2239/1971 Trihey 1. 75/20 F [75] lnventor: Alex R. Valdo, Phoenix, Ariz.FOREIGN PATENTS OR APPLICATIONS [73] Asslgnee Ethyl 1 Rchmond 260,41411/1926 Great Bl'ilflll'l 165/168 [22] Filed; Feb, 26, 1973 615,14710/1926 France 164/79 [2]] Appl. No.: 335,680

. Related US Application Data Prirnary Examiner-Manoel A. Antonakas 63Asszstant Exammer-Dan1el J. O Connor 7 v 1 fgg g g 'g S 5 91 g Attorney,Agent, or Firm-Donald L. Johnson; John F.

1970, a an one an er. 0. 1,212, Nov. 19, Sieberth; Paul H Leonardabandoned.

[52] U.S. Cl 165/168, 164/98, 164/108,

164/112 [57] ABSTRACT [51] Int. Cl. F281 3/12 of Search 99, 79, A foamedmetal panel has a tubular core embedded in 164/112, 134; 237/69 it toconduct heating liquid or the like. The panel can also be reinforcedwith metal inserts such as blocks [56] References Cited and plates atpoints of stress.

4 Claims, 2 Drawing Figures PATENTEQ rm 1 91914 3 848,66 6

HH HP 1 mu 0 mm a FOAMED METAL BODIES CROSS REFERENCES TO RELATEDAPPLICATIONS This application is a continuation-in-part of applicationSer. Nos. 91,211 and now abandoned and 91,212 and now abandoned bothfiled on Nov. 19, 1970.

BACKGROUND OF THE INVENTION Foamed metals are conventionally prepared inrectangular solids. Such bodies are satisfactory for manybuilding orconstruction purposes. A need exists for foamed metal bodies havinghollow corestherein capable of transmitting fluids therethrough,particularly corrosive fluids.

The present invention provides a composite unit of foamed metal andother metals or materials suitable for use in cooling and heatingdevices.

The instant invention also provides light-weight cooling vent units,heat exchange units, evaporative units, and building heating units.

The invention further provides a novel structural body suitable for usein the automobile industry as radiators and the like.

The present invention is also particularly suitable for providing aninsulated fluid conducting means, particularly for carrying corrosivefluids.

SUMMARY OF THE INVENTION The present invention relates to a foamed metalbody having embedded in it a tubular core with a melting point greaterthan that of the foamed metal, and to a method of making such a body.

The foregoing as well as other aspects of the present invention will bemore readily understood from the following description taken with theaccompanying draw- DESCRIPTION OF THE PREFERRED EMBODIMENTS According tothe present invention a rectangular structural panel of foamed aluminumhas embedded therein a conduit of a copper-base metal for a heatingliquid, the conduit having an inlet end and an outlet end, both of saidends projecting out through one face of the panel.

Such a structural panel is particularly desirable for use as a flooringpanel and can for example be made not more than 1 inch thick, and eventhicknesses as little as three-fourth of an inch make suitable flooring.The heating conduit is preferably in the form of a single layer ofconduit lengthsto thus permit the use of conduits having a relativelylarge passageway crosssection.

FIG. 1 shows such a flooring panel 10 fastened directly to floor joists12. This panel can be 8 feet long and 4 feet wide, as in conventionalstructural panels, and is readily nailed in place with headed nails 14.The panel can also be readily trimmed as with a saw if necessary, tomake sure that an edge, as at 16, running parallel to a joist is locatedabout the middle of the joist so that an adjacent panel can also besecured to that joist.

A copper tube 20 is embedded in the panel and has two ends 21, 22 turneddownwardly and projecting through the lowerface of the panel. Those endscan be connected to a conventional hot water home heating circuit sothat the heating water circulates through tube 20. By reason of theintimate contact between the tube and the foamed metal of panel 10 theheat from the heating water is rapidly and efficiently distributedthroughout the panel. Both copper and aluminum have very high thermalconductivities, and with such metals the convolutions of tube 20 can belocated relatively far apart in the panel and less tubing is necessary.Thus tubing having a three-eighths inch internal diameter can be as muchas 15 inches apart if desired. The tubing is preferably kept at leastabout 8 or 10 inches from the edges of the panel to allow the panel tobe trimmed along any or all of its edges.

The nails 14 can have their heads driven into the upper surface of themetal foam, so that they do not penetrate. This leaves a flat panel topsuitable for receiving coatings such as a plastic cover layer over whicha rug or other floor covering can be secured if desired. As withstandard flooring, the edges of the panel that run perpendicular to thejoists can be tongue-and-groove.

The metal foam of the panels is preferably made sufficiently porous sothat the location of tube 20 can be observed from the upper face'of thepanel and the securing nails accordingly located where they do notdamage the tubing. Thus with aluminum foam having a density of about 35pounds per cubic foot a copper tube 20 will have its outline fairlyreliably evident where the top of the tube is not more than aboutonefourth inch below the upper face of the panel. The tube can also belocated closer to that face if desired. By arranging the tube so it iscloser to the upper face than the lower face of the panel, the heatdistribution can be made to favor heating the space above the panel asagainst the space below the panel. Also instead of mounting the paneldirectly on the floor joists 12 it can be mounted on a sheet ofinsulation'or ordinary subflooring, 01'' the lower panel face can becoated with thermally insulating plastic or the like, to also favorheating upwardly as against downwardly.

A single panel may easily be enough to provide all the home heatingnecessary for a small room such as a bathroom or a small kitchen. Forlarger rooms two or more heating panels can be provided either immedi-'ately adjacent each other or in spaced locations. In any of theseconstructions the remainder of the floor around the heating panels canbe filled with additional panels of foamed aluminum that do not containtubing.

A feature of the foregoing floor construction is that it provides afloor surface which is extremely fire resistant and yet simple to build.This is something the building industry has long needed inasmuch asfireresistant wall and ceiling constructions are more or less standardbut the only good fire resistant floors have beenconcrete floors whichare too expensive to provide in individual homes.

The foamed metal panels of the present invention are also simple tosecure in place by cementing, if desired. Thus a layer of cement can bebrushed onto the upper surfaces of the joists 12, after which panel 10can bev lowered in place over the cement-carrying joist surfaces.Unevenesses in level of the top surfaces of the joists 12 can becompensated for by the insertion of shims in any space that appearsbetween the lower face of panel and the upper face of joist 12. Eachshim can carry a top layer of cement to make sure that it is adhered tothe panel as well as to the joist.

Panel 10 can be made by molding the foamed aluminum around the tube 20.FIG. 2 shows such a molding arrangement in which the mold is formed frombottom plate 30, two side plates 31, 32, and two edge plates of whichonly one, 33, is shown in the figure. Each side plate 31, 32 has anumber of openings 41, 42, which receive the ends 21, 22 of a tubefitted into these openings before the mold plates are assembled. A tubeso fitted will remain in place, as shown in FIG. 2, but if desiredadditional supports can be provided such as by use of a length of copperwire looped under a portion of the tube with the ends of wire extendingup over the top edge of the mold.

Molten aluminum containing a foaming agent can then be poured into themold and the foaming completed, and the product cooled as described inUS. Pat. No. 2,979,392 or in other suitable manner. The mold plates canbe made of metal such as carbon steel that is not wet by molten aluminumunder molding conditions. Prior to pouring the molten aluminum into themold, the interior sides of the mold plates are coated with a ladle wash(an iron oxide slurry). The ladle wash is applied before each moldingoperation. After the molding is completed the mold is taken apart, thefoamed block removed from the mold sides and sawn in two to make twopanels of the type shown in FIG. 1.

The molding can also be modified so as to make the foamed block thickerand then sawing it into three or more panels of which only the outer twopanels have the embedded cores. Alternatively only one panel can bemolded at a time, or one core-carrying panel in a plural-panel block.

Foamed aluminum having discrete cells therein may be produced by avariety of methods. They may be produced by expanding molten metalamalgams (British Pat. No. 206,797; US. Pat. Nos. 2,434,775; 2,533,016);by incorporating quartz, microballoons in the molten metal andoptionally heating to expand the gas (Chemical Engineering News, June11, 1962, Page 37); by the use of heavy metal hydride blowing agents,particularly the hydrides of titanium or zirconium (US. Pat. Nos.2,393,906; 2,751,289; 2,895,819; 2,937,938; 2,974,034; 2,979,392;2,983,597); by volatilizing organic materials during cooling of the melt(e.g., camphor as in US. Pat. No. 2,155,651); by volatilizing inorganicsother than metal hydrides (ammonium chloride, U.S. Pat. No. 1,642,348;magnesium carbonate, calcium hydroxide, carbonitrate, US. Pat. No.642,349; calcium carbonate, U.S. Pat. No. 2,191,658; ammoniumbicarbonate, U.S. Pat. No. 2,671,955; cadmium or magnesium carbonate,US. Pat. No. 2,935,396); and by pellet metallurgical techniques(magnesium carbonate growing of magnesium metal, U.S. Pat. No.2,935,396). Other processes involving blowing molten metal with asuitable gas generating agent such as lithium hydride, titanium hydride,zirconium hydride and the like. Air properly entrained in a molten metalmay also be used in preparing such foam. Where a blowing agent such as ametal hydride is used,

'found viscosity control and/or strengthening additives may be used inthe molten metal during the foaming process to help control the foamdensity pore uniformity and provide optimum strength. Representativeexamples of suitable processes for preparing foamed metal are in US.Pat. Nos. 3,297,431, 3,300,296, 3,305,902 and British Pat. No.1,287,994.

The tube 20 can be made of a copper or copper-base alloy such as bronze,brass and the like, where these alloys have melting points higher thanthat required for foaming aluminum. By aluminum is meant substantiallypure aluminum as well as aluminum alloys containing or more andpreferably or more of aluminum. The following aluminum alloys areexamples of useful alloys for preparing the foamed metal bodies of thepresent invention:

Alloy 7075 (1.6% Cu, 2.5% Mg, 0.3% Cr, 5.6% Zn, remainder A1) 2024 (4.5%Cu, 0.6% Mn, 1.5% Mg, remainder A1) 5086 (0.45% Mn, 4.0% Mg, 0.1% Cr,remainder A1) 6063 (0.4% Si, 0.7% Mg, remainder Al) Almag 35 (6-8% Mg inAl) 1000 series A1 (99.6% minimum A1) 2011 (5.5% Cu, 0.5% Pb, 0.5% Bi,remainder A1) 2218 (4.0% Cu, 1.5% Mg, 2% Ni, remainder A1) 3005 (1.2%Mg, 0.4% Mg, remainder Al) 4032 (12.2% Si, 0.9% Cu, 1.1% Mg, 0.9% Ni,re-

mainder A1) 4043 (5% Si, A1)

8280 (1.5% Si, 1.0% Cu, 0.5% Ni, remainder Al) Magnalium 70% Al, 30% MgThe foamed metals used in the present construction may be prepared byprocesses known in the art.

The density of the foamed aluminum may vary over a wide range.Generally, foamed aluminum having a density of less than about 50 pcfcan be used. Foams ranging from 5 to 35 pcf are preferred; densitiesranging below about 27 pcf are more preferred; and a foam densityranging from about 8 to about 27 pcf is most preferred.

The tubular cores may be suspended in the foamed metal mold by anyconvenient means. For example, the core may be suspended or held inplace in the mold by wires. It may also be supported by the mold itself,by spacers secured to or resting against a mold wall, or by shelves orrecesses in the mold or otherwise physically attached to the mold. Theconfiguration, size and shape of the core will in large determine theparticular type of suspension to be chosen.

. If fluids are to be transported or moved through the tubular bodyencapsulated in the foamed metal, the bodywill be held in place in themold so that fluid communication can be readily obtained in the finishedproduct. For example, openings in the tubular body will extend throughthe encapsulation to a desired degree.

The panels of the present invention are also suitable for interiorpanels of a freezing compartment with foamed metal. The tubular core isfor this purpose connected so as to receive the freon or other coolantsused in the evaporator of the refrigeration system.

The instant invention may also be used for constructing wall panels orthe like, wherein steam or other suitable heating fluids may betransferred through tubular bodies encapsulated in the foamed metal.Thus the panel of FIG. 1 makes a good roof covering that collects solarheat which is transmitted to avenues of a liquid circulated through tube20, to a panel within a home where it serves to heat the home. A roofpanel of this kind can be much thinner than three-fourth inch.

Where the foamed aluminum panels are subject to excessive stresses theycan be reinforced as by embedded blocks or the like. The tube in thepanel of FIG. ll also acts as a reinforcement, particularly where thetube is made of thickwalled hard brass or bronze, or of steel. Also byplacing a length of such a tube under longitudinal tension in the moldand then releasing that tension after the molded panel has solidifiedand cooled somewhat, the panel is placed under some internal compressionthat further strengthens it. The effect of such internal compression isincreased when the tensioned tube length has flanges at each end thatengage the surrounding metal foam.

Reinforcing blocks or plates may also be embedded in the foamed metal atdesired stress locations for facilitating the joining of panels, as forexample to make a cargo container or other box-like structure from thepanels, or to strengthen tongue-and-groove interengagements betweenpanels. Such embedded bodies can extend to the surface of the panelwhere the bodies are used to receive fasteners such as screws, bolts orrivets or other desired hardware. Hinges and handles can thus be appliedas well as locks or catches.

The reinforcing bodies can be of metals such as copper, brass, steel ortitanium, that have melting points higher than that of the aluminumfoamed. Where these bodies are to extend to the surface of the finalpanel, they can be secured to the mold surface, as by screws or the likethat penetrate through the mold plate and threadedly engage the body,preferably at a threaded opening provided for receiving a fastener inthe completed panel. Reinforcing bodies that do not extend to the panelssurface can be held in the mold by wires, shelves, spacers, or the like,as in the case of the tubing.

The foamed panels can also be reinforced by distributing in the foamedmetal some reinforcing fibers. Such fibers can be made of metal such asbrass, bronze, copper, steel, titanium, or they can be made of carbon orother inorganic materials that withstand the temperatures producedduring the foaming operation. It is preferred that the fibers be atleast about one-half inch long, although even fiber lengths ofone-fourth inch are helpful.

Although copper is the preferred material for the conduits of thisinvention, other suitable materials having a higher melting point thanthat of the foamed metal comprising the panel or body. Some examples ofthese materials are zirconium, tantalum, titanium, steel and alloys ofthese materials. Other examples are carbides, borides, nitrides,graphite, silicon, zirconia and refractory or ceramic materials.

The foregoing disclosure and description of the invention isillustrative and explanatory thereof and various changes in the size,shape and materials as well as in the details of the describedconstruction, may be made within the scope of the appended claimswithout departing from the spirit of the invention.

What is claimed is:

1. A rectangular structural panel of foamed aluminum having discretecells therein, having a density less than about 50 pounds per cubic footand having embedded therein a copper-base conduit for a heating liquid,the conduit having an inlet and an outlet end, both of said endsprojecting out through one face of the panel.

2. The combination of claim 1 in which the panel is not more than about1 inch thick and the conduit is in the form of a single layer.

3. A rectangular structural panel of heat conducting foamed aluminumhaving discrete cells therein and receiving fasteners or other desiredhardware. v

1. A rectangular structural panel of foamed aluminum having discretecells therein, having a density less than about 50 pounds per cubic footand having embedded therein a copper-base conduit for a heating liquid,the conduit having an inlet and an outlet end, both of said endsprojecting out through one face of the panel.
 2. The combination ofclaim 1 in which the panel is not more than about 1 inch thick and theconduit is in the form of a single layer.
 3. A rectangular structuralpanel of heat conducting foamed aluminum having discrete cells thereinand having embedded therein a copper-base conduit for a heating liquid,the conduit having an inlet and an outlet end, both of said endsprojecting out through one face of the panel, and reinforcing blocks orplates embedded in the foamed metal at desired stress locations forstrengthening the panel or facilitating the joining of one panel toanother panel.
 4. The panel of claim 3, wherein said reinforcing blocksor plates extend to the surface of the panel for receiving fasteners orother desired hardware.